231. Power of Two-2的幂

Given an integer n, return true if it is a power of two. Otherwise, return false.

An integer n is a power of two, if there exists an integer x such that n == 2x.

Example 1:
Input: n = 1
Output: true
Explanation: 20 = 1

Example 2:
Input: n = 16
Output: true
Explanation: 24 = 16

Example 3:
Input: n = 3
Output: false

Example 4:
Input: n = 4
Output: true

Example 5:
Input: n = 5
Output: false

Constraints:

• -2^31 <= n <= 2^31 – 1

Solution in python:

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        if n <= 0:
            return False
        if n == 1:
            return True
        else:
            while n > 1:
                n, r = divmod(n, 2)
                if r == 1:
                    return False
            return True